FlyLow

For researchers, it would be ideal if the aircraft flew three feet above the ground at the same speed the onboard computers where capable of collecting data (i.e. very low and very quickly). But a method has been developed so you fly at an altitude of 200 feet and a speed of 135 knots instead, and still get good enough data for the researchers. The selected altitude and speed is based on safety and on the airplanes performance, efficiency and fuel economy. The flight route is a imaginary line in the air, usually in an east-west direction (or opposite). The length of the lines varies, but are usually from a few kilometers up to a hundred kilometers long. At the end of each line, you climb slightly, make a turn and then descend down to your low survey altitude again and fly back in the opposite direction, 200 meters parallel from the line you just flew. You continue to fly the lines, back and forth - much like when you harvest a field - until the whole area is completed. During favorable conditions, it is possible to fly up to 600 km at a single mission, which corresponds to a 120 km² area.

All the flights are preformed manually without any autopilot, but a specially developed GPS is installed to assist the Pilot, and also a radar altimeter. At the cockpits right seat the Navigator is seated. Prior to the flight, the Navigator assist the Pilot and reconnoiter the aerial maps and the expected obstacles. During the flight the Navigator keep track of the position and inform the pilot about any obstacles. Examples of obstacles are power lines, masts, wind turbines and high towers of various kinds. When you pass lower obstacles such as mobile phone masts and wind turbines (usually around 260 feet high) you usually climb slightly and passes them on top. Higher obstacles, such as TV- and radio masts (which may be up to 1000 feet high, and often have long and wide supporting wires) you fly around and passing them at a safe distance. At these high mast locations no data can be collected, but the blank spots is relatively small and the data can often be interpolated at these locations.

The requirements for operations at low altitudes are high. You have to fly low and fast with high precision, without compromise the safety. The low altitude means that you also are exposed to significantly higher strain than at "normal" flight. Including, risk of bird strikes are significant higher and the constant need to adopt to the underlying terrain variations and various obstacles. Moreover, flights at low altitude means that you are often exposed to greater turbulence due to the wind (ground friction), but also because of the sun is heating up the ground during daytime. To avoid that, the flights are taking placed during the times of day when the wind is weak and the solar radiation are low, i.e. usually during early mornings and late evenings. (With the consequence that the crew often gets blinded by the low sun). Furthermore, the crew must all the time keep an eye out for other low-flying aircraft and helicopters, especially if you are operating in the vicinity of an airport.

In other words, flying low leads to higher risks and greater pressures on both human and material, but with proper training, good planning and right attitude of the flying crew, these special low altitude missions are as safe as "normal" flight.

In order to legally operate an aircraft professionally at low altitudes the Aviation Authorities requires that you posses a so-called Low Flying License. Such license is issued by the companies engaged in the aerial work at low altitudes and is limited to be valid only for professional use. The training includes both theory and practice.